Question

How do you convert between energy units: 231 cal to kJ?

Answer 1

Hint: A body consumes some energy while performing work. This energy is expressed in various units like, calorie, kilocalorie, joule, kilo joules, etc.

Complete answer:
A calorie is considered as the energy required raising the temperature of one Kg water by one degree Celsius. While, joule is the SI unit of energy.
These two units of energies are inter-convertible. As one joule is equal to 0.239 calories. Through this conversion term, we can derive the given 231 calories into kilojoule as.
231 cal = $\dfrac{231\,cal}{0.239\,cal\,{{J}^{-1}}}$
So, 231 cal to joule = 966.5 $\dfrac{1}{{{J}^{-1}}}$
231 cal into joule = 966.5 J
As we know 1 kilo joule = 1000 joules
We have, $\dfrac{966.5\,J}{1000\,kJ\,.\,J}$ = 0.966 kJ $\simeq $ 1 kJ
Hence, the conversion of 231 calories into kilojoules is 0.966 kJ or 1 kJ.

Additional information:
Calories are the unit of energy which we can see at the label of food products, while kilocalorie is employed in the terms of energy other than food products. Joule is that unit of energy that acts on with a force of one Newton on an object under the area of one meter square.

Note:
We have seen that one joule is 0.239 calories, but also 1 calorie has a conversion into joule as, 1 cal = 4.1833 joules. While 1000 calories make up to 1 kilocalorie while considering the energy in food consumption.